Re: Streams support in Linux

Matthew Wilcox
2018-08-27T22:09:45Z

On Mon, Aug 27, 2018 at 10:05:31AM -0700, Jeremy Allison wrote:
> I can't think of a *single* case where a stream adds more
> utility than an EA used in the same case.
>
> I don't want theoretical "well it would be nice if..",
> I want clear "we couldn't have done it any other way"
> kinds of things.

I started this thread with such an example. The fs-verity patch proposed
wants to store hundreds of megabytes of data associated with a particular
file. The current solution is to append it to the end of the data then
magic to set i_size lower but not remove the data from the file like a
truncate would. Then more magic to read that data.

It can't be stored in an xattr; xattrs are limited to 64k in size.
And you have to read them / write them all-in-one-go; you can't read
a little bit of them. How would you solve the fs-verity problem with
less magic?